(Supplementary data) - Is predictability of randomisation a historic concern: A survey of practice of recruiters to randomised controlled trials

Supplementary data for publication of the results of a survey: Randomisation in randomised controlled trials (RCTs) is intended to guard against selection bias by creating unpredictable sequences. Some randomisation methods, however, aim to achieve better balance between groups being compared at the expense of predictability. This study aims to investigate the extent to which recruiters into RCTs attempt to predict upcoming allocations, hence how concerned trialists should be about using more predictable randomisation methods.